What does the suffix -ist mean in the word pianist?

What does water came out from a rock mean in this poem and why is it compared to the radio waltz? time was away and somewhere else. the waiter did not come, the clock forgot them and the radio waltz came out like water from a rock: time was away and somewhere else.

Composition about "the day i ran away" with 500 words

Which if the following does the communist party do through it's party organization? select all that apply.ensures freedom of the people recruits members and leaders develops policy indoctrinates the people maintains discipline